MDHearing VoltMax vs Olive Union Air
Side-by-side HearAdvisor lab results with SoundGrades, expert pick badges, and the same visualizations we use in product reviews.

MDHearing VoltMax
The MDHearing VoltMax is a behind-the-ear OTC hearing aid priced at $699, earning a B grade with a SoundScore of 3.0/5 in our lab testing. This places it in the lower tier of the OTC hearing aid category, ranking 62nd out of 65 devices tested. In our testing, the VoltMax delivered mixed results across key performance areas. Its standout strength is excellent feedback handling, scoring a perfect 5.0/5—above the category average by 0.46 points. This means users can expect stable performance without whistling or squealing during typical daily activities. However, speech clarity proved challenging, with speech-in-quiet scoring 1.9/5 (0.93 points below category average) and speech-in-noise at 1.0/5 (0.48 points below average). Own-voice comfort measured 2.4/5, slightly below the category norm. A significant limitation is music streaming, which scored 0.0/5—nearly 2 points below the category average. Users who prioritize phone streaming for calls or media should consider alternatives. The device features rechargeable batteries, offering convenience over disposable options. At this price point, several competitors deliver substantially stronger overall performance. The VoltMax may appeal to budget-conscious consumers who primarily need basic amplification with reliable feedback control and don't require streaming capabilities. Those seeking better speech clarity or music streaming should explore higher-scoring options in this price range.

Olive Union Air
The Olive Union Air is a budget-priced OTC hearing aid that earned a B grade with a SoundScore of 3.9/5 in our lab testing, placing it in the top 31% of OTC hearing aids at #21 of 65 devices tested. At $250, it represents a competitive entry point in the over-the-counter hearing aid market. In our testing, this visible-in-ear style device demonstrated notable strengths in music streaming, scoring 3.6/5—a solid result that sits 1.67 points above the OTC category average. Feedback handling was excellent at 5.0/5, meaning users should experience minimal whistling or squealing during normal use. Speech understanding in quiet environments also performed well at 3.3/5, measuring 0.46 points above the category average. The Olive Union Air does show limitations in more challenging listening situations. Speech in noise scored 1.0/5, falling 0.48 points below the category average—a common weakness among budget OTC devices that may affect conversations in restaurants or busy environments. Own-voice comfort measured 2.2/5, slightly below average, which some users may notice when speaking. This device is best suited for individuals who prioritize music and media streaming, need reliable feedback control, and primarily listen in quieter environments. Those who frequently encounter noisy social situations may want to consider devices with stronger speech-in-noise performance.
Performance metrics
Scale 1-5 (Tuned)
Lab metric by fit
Scale 1-5 (Tuned)
Speech level
Adjust input dB (Tuned)
Amplification (REIG)
Insertion gain at 65 dB (Tuned)
Audio scenes
Recorded samples (Tuned)
Fitting configuration for tuned fit